CN110323749A - The disturbance restraining method of LCL filter gird-connected inverter - Google Patents
The disturbance restraining method of LCL filter gird-connected inverter Download PDFInfo
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
- H02J3/00—Circuit arrangements for ac mains or ac distribution networks
- H02J3/01—Arrangements for reducing harmonics or ripples
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
- H02J3/00—Circuit arrangements for ac mains or ac distribution networks
- H02J3/38—Arrangements for parallely feeding a single network by two or more generators, converters or transformers
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
- H02M1/00—Details of apparatus for conversion
- H02M1/12—Arrangements for reducing harmonics from ac input or output
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02J—CIRCUIT ARRANGEMENTS OR SYSTEMS FOR SUPPLYING OR DISTRIBUTING ELECTRIC POWER; SYSTEMS FOR STORING ELECTRIC ENERGY
- H02J2203/00—Indexing scheme relating to details of circuit arrangements for AC mains or AC distribution networks
- H02J2203/20—Simulating, e g planning, reliability check, modelling or computer assisted design [CAD]
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
- Y02E40/00—Technologies for an efficient electrical power generation, transmission or distribution
- Y02E40/40—Arrangements for reducing harmonics
Abstract
The present invention is the disturbance restraining method of LCL filter gird-connected inverter.LCL filter is converted to first-order system by the present invention, designs LCL filter single order from jamproof system model；Simplify LCL filter single order from jamproof system model, input signal passes through Nonlinear Tracking Differentiator, lists transient behaviour by Nonlinear Tracking Differentiator, and calculate the all-order derivative of input signal；Extended mode observer calculates the equation of line style extended mode observer, and by second order line style extended mode observer, estimated state variable and total disturbance are integrated with own resonance by disturbing；To state error carry out feedback control, future Nonlinear Tracking Differentiator reference signal and extended mode observer output difference signal combine, generate intermediate control voltage signal；Selection observer gain devises an independent single order line type control device to each current component, inhibits to external disturbance and internal interference so that observer characteristic value is in stable state.
Description
Technical field
The present invention relates to LCL filter technical fields, are a kind of disturbance restraining methods of LCL filter gird-connected inverter.
Background technique
In recent years, global energy anxiety and environmental pollution is getting worse, in order to solve energy crisis and the protection mankind
The environment depended on for existence, finding new energy becomes present matter of utmost importance.Solar energy, wind energy, tide energy etc. belong to can
Regenerated clean energy resource.Distributed power generation just has been more and more widely used, the important shape as renewable energy utilization
Formula, these can be divided into off-network power generation according to different applications and grid-connected system, off-grid system are to convert solar energy
Electric energy be stored in battery, user equipment is then supplied by controller.Grid-connected system is the electricity with electric system
Net is connected, and the electric energy of conversion is connected to the grid, and then distributes electric energy unitedly to user by power grid.Grid-connected system, which has, exempts to tie up
The advantages that protecting and be at low cost, therefore main sight is put into generating electricity by way of merging two or more grid systems using gird-connected inverter as core by domestic and foreign scholars
Technology, parallel net type electricity generation system become the mainstream of Developing.
Inverter plays an important role in terms of connection power grid and the energy, and the control strategy of gird-connected inverter causes device defeated
Contain a large amount of switching frequency subharmonic in voltage waveform out, in order to reduce the HF switch present in electric current that is connected to the grid
Harmonic wave obtains the high grid-connected current of sine degree, needs to choose suitable filter in inverter outlet side.Common filter
Mainly there are L-type and two kinds of LCL type.Compared with L-type filter topologies, LCL type filter increases capacitive branch, makes it to height
Subharmonic presentation is high resistance, more preferable to the inhibitory effect of higher hamonic wave, and when filter effect is identical, LCL filter tool
There are better high-frequency harmonic Decay Rate, smaller device size and lower cost, therefore receives significant attention.Traditional LCL
Filter shows very big impedance for high-frequency harmonic electric current, but for the impedance very little of the harmonic wave of certain specific frequencys performance,
The harmonic current of these specific frequencys is not but not suppressed, can be amplified instead by LCL filter.Traditional passive damping method,
Such as in LCL filter capacitive branch series damping resistor, damping of the filter at resonance frequency is increased.But the nothing introduced
Source damping resistance brings excess loss, and converter is caused to generate heat.But this filter needs to take there are resonance problems
Method inhibits resonance, it is ensured that the stability of system.Meanwhile the microvariations of network voltage can greatly increase inverter injection power grid
Current distortion rate, it is unstable to may cause system.So to take steps to inhibit the unknown disturbances and LCL itself of power grid
The resonance of initiation.
To solve this problem it is necessary to increase active damping control and AF panel control in control, at least need
Two control loops.External disturbance and own resonance are considered as one by the present invention, reduce control loop.
Summary of the invention
The present invention be solve network voltage microvariations can greatly increase inverter injection power grid current distortion rate, and
Cause system shakiness in the uncertain problem of electrical network parameter, the present invention provides a kind of interference of LCL filter gird-connected inverter
Suppressing method, the present invention provides following technical schemes:
A kind of disturbance restraining method of LCL filter gird-connected inverter, includes the following steps:
Step 1: being converted to first-order system for LCL filter, designs LCL filter single order from jamproof system model；
Step 2: simplifying LCL filter single order from jamproof system model, and input signal passes through Nonlinear Tracking Differentiator, by with
Track differentiator lists transient behaviour, and calculates the all-order derivative of input signal；
Step 3: extended mode observer calculates the equation of line style extended mode observer, extends shape by second order line style
State observer, estimated state variable and total disturbance, it is integrated with own resonance by disturbing；
Step 4: to state error carry out feedback control, future Nonlinear Tracking Differentiator reference signal and extended mode observation
The output difference signal of device combines, and generates intermediate control voltage signal；
Step 5: selection observer gain designs each current component so that observer characteristic value is in stable state
One independent single order line type control device, inhibits external disturbance and internal interference.
Preferably, the step 1 specifically: LCL filter is converted into single order L-type filter system, design LCL filter
Wave device single order indicates the LCL filter from jamproof system model from jamproof system model, by following formula:
Wherein,Be LCL filter single order from the output signal of jamproof system, f (t, y, w) be estimation need to mitigate it is total
Interference, w is external interference signals, and t is the time, and y represents input signal, and u is the reference input of inverter, and b is system parameter.
Preferably, the step 2 specifically:
The first step simplifies LCL filter single order from jamproof system model, f (t, y, w) is extended as vector shape
State indicates the differential equation of vector state by following formula:
Wherein,For the differential of vector state, x (t) vector state, u (t) is the second vector state,To assume
Differential, y (t) are extended mode, and A, B, C, E respectively represent sytem matrix, control matrix, output matrix and perturbation matrix；
Step 3: input signal passes through Nonlinear Tracking Differentiator, the all-order derivative of input signal is calculated, indicates defeated by following formula
Enter the all-order derivative of signal:
Wherein, vnIt is input signal,It is the derivative of input signal, ψ is closure function, and n is systematic education, and r is speed
The factor.
Preferably, the step 3 specifically:
Step 1: simplifying LCL filter single order from jamproof system model, constructed on simplified LCL filter model
Corresponding second order line style extended mode observer, indicates the second order line style extended mode observer by following formula:
Wherein,For the differential of second order line style extended mode observer, z (t) is second order line style extended mode observer
Output, L be second order line style extended mode observer gain vector, TdFor time delay module,For ideal power grid electricity
Stream；
Step 2: second order line style extended mode observer state z1And z2Y and f (t, y, w) will be tracked respectively；
Step 3: estimated state variable and total disturbance, will always disturb and own resonance integration.
Preferably, it is calculate by the following formula the gain vector of second-order linearity extended mode observer:
L=[β1β2]T (6)
Wherein, β1、β2It is adjustment parameter, T is it is expected to stablize the time.
Preferably, Laplace transform is carried out to second-order linearity extended mode observer expression formula and obtains the observer shape
State z1And z2, z is indicated by following formula1And z2:
Wherein, s is Laplace operator, and r is reference input, and kp is controller gain.
Preferably, the step 4 specifically:
Step 1: carrying out feedback control to state error, SEF is by the reference signal from TD and from the observer of ESO
Output difference signal combines, and generates the intermediate voltage signal u controlled using nonlinear function0；
Step 2: compensating total disturbance in suppression loop, compensated total disturbance is indicated by following formula:
Wherein, u is compensated total disturbance, u0For using the voltage signal of the terminal point control on nonlinear function birthdate；
Step 3: output signal and input signal are indicated by following formula after suppression loop compensates total disturbance:
Wherein, kp is controller gain.
Power grid is considered as pure integral element, is controlled using linear scale controller, the linear scale is indicated by following formula
Controller:
U (t)=kp(t(t)-z1(t)) (11)
Wherein, u (t) is linear scale controller, and t (t) is reference input, z1It (t) is to actually enter.
Preferably, the step 5 specifically:
Step 1: determining closed-loop pole according to desired stable time T, controller gain is obtained, observer is selected to increase
Benefit, so that all observer characteristic values are all located at-ωo, then have at this time:
Wherein, ωoFor observer bandwidth；
Step 2: obtaining the control strategy of control when observer characteristic value is in stable state, indicate to control by following formula
System strategy:
U (s)=Gc(s)(r(s)-H(s)y(s)) (13)
Wherein, u (s) is control strategy, GcIt (s) is controlling unit transmission function, H (s) is feedback element transmission function, r
It (s) is input signal function, y (s) is output signal function；
Step 3: acquiring control output in a frequency domain, indicate that control in a frequency domain exports by following formula:
Y (s)=Gfy(s)f(s)+Gry(s)r(s) (16)
Wherein, f (s) is disturbance, GfyIt (s) is disturbance transfer function, Gry(s) reference input transmission function.
Preferably, when ignoring disturbance, then simplified control exports expression formula, indicates that simplified control exports by following formula
Expression formula:
The invention has the following advantages:
It is good that the present invention realizes that LCL filter gird-connected inverter current control all has external disturbance and internal disturbance
Unknown dynamic and interference can actively be estimated in real time and be compensated to robustness, control method so that feedback control more it is stable simultaneously
And it is less dependent on detailed mathematical model in practice.Controlling model is established, ginseng is determined according to its stability and tracing property
Number inhibits external disturbance and LCL own resonance.Therefore, even if being proposed in the case where Parameter uncertainties and power grid interfere
Current controller also quick response and can have good stability.
Detailed description of the invention
Fig. 1 is the control block diagram of first-order linear controller；
Fig. 2 is the Bode diagram of Gfy when changing bandwidth omega c；
Fig. 3 is the Bode diagram of Gfy when changing observer bandwidth omega o；
Fig. 4 is network voltage and power network current under rated power；
Power network current when Fig. 5 power grid inductance changes；
Network voltage and power network current under Fig. 6 grid disturbances.
Specific embodiment
Below in conjunction with specific embodiment, describe the invention in detail.
Specific embodiment one:
According to block diagram shown in Fig. 1, the present invention provides a kind of disturbance restraining method of LCL filter gird-connected inverter, including
Following steps:
Step 1: being converted to first-order system for LCL filter, designs LCL filter single order from jamproof system model；
Step 2: simplifying LCL filter single order from jamproof system model, and input signal passes through Nonlinear Tracking Differentiator, by with
Track differentiator lists transient behaviour, and calculates the all-order derivative of input signal；
Step 3: extended mode observer calculates the equation of line style extended mode observer, extends shape by second order line style
State observer, estimated state variable and total disturbance, it is integrated with own resonance by disturbing；
Step 4: to state error carry out feedback control, future Nonlinear Tracking Differentiator reference signal and extended mode observation
The output difference signal of device combines, and generates intermediate control voltage signal；
Step 5: selection observer gain designs each current component so that observer characteristic value is in stable state
One independent single order line type control device, inhibits external disturbance and internal interference.
Further, the step 1 specifically: LCL filter is converted into single order L-type filter system, designs LCL
Filter single order indicates the LCL filter from jamproof system model from jamproof system model, by following formula:
Wherein,Be LCL filter single order from the output signal of jamproof system, f (t, y, w) be estimation need to mitigate it is total
Interference, w is external interference signals, and t is the time, and y represents input signal, and u is the reference input of inverter, and b is system parameter.
Further, the step 2 specifically:
The first step simplifies LCL filter single order from jamproof system model, f (t, y, w) is extended as vector shape
State indicates the differential equation of vector state by following formula:
Wherein,For the differential of vector state, x (t) vector state, u (t) is the second vector state,To assume
Differential, y (t) are extended mode, and A, B, C, E respectively represent sytem matrix, control matrix, output matrix and perturbation matrix；
Step 3: input signal passes through Nonlinear Tracking Differentiator, the all-order derivative of input signal is calculated, indicates defeated by following formula
Enter the all-order derivative of signal:
Wherein, vnIt is input signal,It is the derivative of input signal, ψ is closure function, and n is systematic education, and r is speed
The factor.
Further, the step 3 specifically:
Step 1: simplifying LCL filter single order from jamproof system model, constructed on simplified LCL filter model
Corresponding second order line style extended mode observer, indicates the second order line style extended mode observer by following formula:
Wherein,For the differential of second order line style extended mode observer, z (t) is second order line style extended mode observer
Output, L be second order line style extended mode observer gain vector, TdFor time delay module,For ideal power grid electricity
Stream；
Step 2: second order line style extended mode observer state z1And z2Y and f (t, y, w) will be tracked respectively；
Step 3: estimated state variable and total disturbance, will always disturb and own resonance integration.
Further, it is calculate by the following formula the gain vector of second-order linearity extended mode observer:
L=[β1β2]T (6)
Wherein, β1、β2It is adjustment parameter, T is it is expected to stablize the time.
Further, Laplace transform is carried out to second-order linearity extended mode observer expression formula and obtains the observer
State z1And z2, z is indicated by following formula1And z2:
Wherein, s is Laplace operator, and r is reference input, and kp is controller gain.
Further, the step 4 specifically:
Step 1: carrying out feedback control to state error, SEF is by the reference signal from TD and from the observer of ESO
Output difference signal combines, and generates the intermediate voltage signal u controlled using nonlinear function0；
Step 2: compensating total disturbance in suppression loop, compensated total disturbance is indicated by following formula:
Wherein, u is compensated total disturbance, u0For using the voltage signal of the terminal point control on nonlinear function birthdate；
Step 3: output signal and input signal are indicated by following formula after suppression loop compensates total disturbance:
Wherein, kp is controller gain.
Power grid is considered as pure integral element, is controlled using linear scale controller, the linear scale is indicated by following formula
Controller:
U (t)=kp(t(t)-z1(t)) (11)
Wherein, u (t) is linear scale controller, and t (t) is reference input, z1It (t) is to actually enter.
Further, the step 5 specifically:
Step 1: determining closed-loop pole according to desired stable time T, controller gain is obtained, observer is selected to increase
Benefit, so that all observer characteristic values are all located at-ωo, then have at this time:
Wherein, ωoFor observer bandwidth；
Step 2: obtaining the control strategy of control when observer characteristic value is in stable state, indicate to control by following formula
System strategy:
U (s)=Gc(s)(r(s)-H(s)y(s)) (13)
Wherein, u (s) is control strategy, GcIt (s) is controlling unit transmission function, H (s) is feedback element transmission function, r
It (s) is input signal function, y (s) is output signal function；
Step 3: acquiring control output in a frequency domain, indicate that control in a frequency domain exports by following formula:
Y (s)=Gfy(s)f(s)+Gry(s)r(s) (16)
Wherein, f (s) is disturbance, GfyIt (s) is disturbance transfer function, Gry(s) reference input transmission function.
Further, when ignoring disturbance, then simplified control exports expression formula, indicates that simplified control is defeated by following formula
Expression formula out:
Specific embodiment two:
It is approximately first first-order system by LCL filter, design controller and approximate LCL filter on this basis is
Model of uniting is as follows:
In formula: f (t, y, w) indicates to estimate the total interference for needing to mitigate, including external disturbance w and internal dynamic, t generation
Table time, y represent power network current, and u is the reference input of inverter, and b is system parameter.
Input signal passes through Nonlinear Tracking Differentiator link, calculates the all-order derivative of input signal.For first-order system, output
Y is defined as first state x1；Total disturbance f is defined as extended mode x2.Assuming that f be it is differentiable, above add some points and represent differential, be
Model expression formula in the state space of vector state x of uniting is as follows:
In formula:
C=(1 0)
Wherein, A, B, C, E respectively represent sytem matrix, control matrix, output matrix and perturbation matrix.Then, in simplification
LCL filter model on construct respective extension state observer:
In formula: L=[1 β 2 of β] T is the gain vector of observer, and z represents observer output, and β 1, β 2 is adjustment parameter.
Further, SEF combines the reference signal from TD and the observer output difference signal from ESO, and use is non-
Linear function generates the voltage signal u0 of intermediate control.
Finally, compensating total disturbance in Disturbance Rejection loop, the expression formula of u is as follows:
The relationship of output signal and input signal can indicate as follows:
Y represents output signal and power grid is considered as pure integral element, is controlled using the linear scale controller of following form:
U (t)=kp(t(t)-z1(t))
In formula: kp is controller gain.
When determining above-mentioned parameter, Laplace transform is carried out to extended mode observer first and obtains following expression:
In formula, r is reference input, behalf Laplace operator.
According to the extended mode observer after total disturbance u, linear scale controller control u (t) and Laplace transform
Expression formula z1With middle z2, the control law that can be further acquired controller is as follows:
U (s)=Gc(s)(r(s)-H(s)y(s))
R (s) and y (s) is respectively input signal and output signal in formula, and the expression of Gc (s) and H (s) is as follows:
The expression formula for finally acquiring control output in the domain s is as follows:
In formula, GfyIt (s) is disturbance transfer function, GryIt (s) is reference input transmission function.
If ignoring disturbance f (s), simplified output expression formula are as follows:
It can thus be appreciated that stability margin increases, and tracking velocity is faster by increasing control bandwidth；Increase observer bandwidth or control
Device bandwidth processed has better anti-interference.
Design for controller determines closed-loop pole according to desired stable time T, obtains controller gain kp.Cause
This has:
kp=-ωc, and
Selection observer gain has at this time so that all observer characteristic values are all located at-ω o:
β1=2 ωo,
Finally, b value is gradually increased until and meets dynamic property.
Specific embodiment three:
Output signal is obtained by the signal of Nonlinear Tracking Differentiator as difference by linear expansion state observer with input signal
Differential signal, and control it.Present embodiment is suitble to realize use under there are the power grid of various disturbances to be a kind of
The method of the inverter Robust Current control of LCL filter, to realize the active suppression to external disturbance and internal interference.By
It will appear disturbance in the reason of network load or electric network fault etc., power grid, cause the resonance of LCL filter, lead to system not
Stablize.This requires current controls still can the grid-connected current of high quality in the case where having and disturbing.Specific such as Fig. 1, can
To find out, which mainly includes two control loops.Inner ring, referred to as AF panel ring are responsible for the total disturbance of compensation；Outer ring claims
For feedback control loop, desired signal is realized by feedback controller.Wherein, w is external disturbance, and b is given constant, kpFor control
Device gain processed.
Step 1 replaces the third-order system of LCL filter with first-order system, establishes based on approximate LCL filter model
Single order control system mathematical model.Output signal is y, input signal u, interference signal w, such as Fig. 1.
Step 2 tracks differentiation, is based on simplified system model, is listed transient behaviour by Nonlinear Tracking Differentiator and calculated
The all-order derivative of input signal, v are input signal, vi(i=1,2 ..., n) be output signal, n indicates systematic education.
Step 3, linear expansion state observer, estimation Obj State variable and total disturbance, disturbance and own resonance are regarded
It is integrated, the equation of linear expansion state observer is calculated based on simplified model.
Step 4, to state error progress feedback control, the reference signal of autotracking in future differentiator and from extension shape
The observer output difference signal of state observer combines, and intermediate control voltage signal u is generated using nonlinear function0。
Step 5: in conjunction with Fig. 2 and Fig. 3, wherein Fig. 2 is to change control bandwidth ωcWhen low-pass filter Bode diagram；Fig. 3
To change observer bandwidth omegaoWhen Gfy Bode diagram, be based on this, the tracing property and stabilization of system are studied according to frequency response
Property.According to desired stable time TsettleIt determines closed-loop pole, obtains controller gain.Observer gain is selected, so that seeing
It surveys device characteristic value and is in stable state.Finally, b value is gradually increased until and meets dynamic property.
Step 6: an independent first-order linear controller is devised for each current component, to external disturbance and inside
Interference, which is realized, to be inhibited, and obtains current waveform figure and current harmonics analysis chart as shown in Fig. 4 to Fig. 6.Wherein, it is based on active damping
Robust Current control simulation result it is as shown in Figure 4.Power network current is adjusted to rated value, and identical as electric network voltage phase,
As shown in Fig. 4.In the case where Parameters variation, the power network current waveform of the Robust Current control based on active damping control is imitated
True result is as shown in Figure 5, it can be seen that stability and high efficiency also may be implemented in the case where Parameters variation in Robust Current control
Control.And as seen in Figure 6, there are grid disturbances, Robust Current control still can well with
Track refers to power network current, inhibits grid disturbance using active AF panel policy control, obtains good stability.
The above is only the preferred embodiment of the disturbance restraining method of LCL filter gird-connected inverter, LCL filter
The protection scope of the disturbance restraining method of gird-connected inverter is not limited merely to above-described embodiment, all skills belonged under the thinking
Art scheme all belongs to the scope of protection of the present invention.It should be pointed out that for those skilled in the art, not departing from this hair
Several improvements and changes under the premise of bright principle, such modifications and variations also should be regarded as protection scope of the present invention.
Claims (9)
1. a kind of disturbance restraining method of LCL filter gird-connected inverter, it is characterized in that: including the following steps:
Step 1: being converted to first-order system for LCL filter, designs LCL filter single order from jamproof system model；
Step 2: simplify LCL filter single order from jamproof system model, input signal passes through Nonlinear Tracking Differentiator, micro- by tracking
Divide device to list transient behaviour, and calculates the all-order derivative of input signal；
Step 3: extended mode observer calculates the equation of line style extended mode observer, is seen by second order line style extended mode
Device, estimated state variable and total disturbance are surveyed, it is integrated with own resonance by disturbing；
Step 4: carrying out feedback control to state error, future Nonlinear Tracking Differentiator reference signal and extended mode observer
Output difference signal combines, and generates intermediate control voltage signal；
Step 5: selection observer gain devises one to each current component so that observer characteristic value is in stable state
A independent single order line type control device, inhibits external disturbance and internal interference.
2. a kind of uncertain parameter disturbance restraining method of LCL filter gird-connected inverter according to claim 1, special
Sign is:
The step 1 specifically: LCL filter is converted into single order L-type filter system, design LCL filter single order is certainly anti-
Interference system model indicates the LCL filter from jamproof system model by following formula:
Wherein,It is LCL filter single order from the output signal of jamproof system, f (t, y, w) is total interference that estimation need to mitigate,
W is external interference signals, and t is the time, and y represents input signal, and u is the reference input of inverter, and b is system parameter.
3. a kind of uncertain parameter disturbance restraining method of LCL filter gird-connected inverter according to claim 1, special
Sign is: the step 2 specifically:
The first step, simplifies LCL filter single order from jamproof system model, and f (t, y, w) is extended as vector state, is led to
Crossing following formula indicates the differential equation of vector state:
Wherein,For the differential of vector state, x (t) vector state, u (t) is the second vector state,To assume differential,
Y (t) is extended mode, and A, B, C, E respectively represent sytem matrix, control matrix, output matrix and perturbation matrix；
Step 3: input signal passes through Nonlinear Tracking Differentiator, the all-order derivative of input signal is calculated, input letter is indicated by following formula
Number all-order derivative:
Wherein, vnIt is input signal,It is the derivative of input signal, ψ is closure function, and n is systematic education, and r is velocity factor.
4. a kind of uncertain parameter disturbance restraining method of LCL filter gird-connected inverter according to claim 1, special
Sign is: the step 3 specifically:
Step 1: simplifying LCL filter single order from jamproof system model, constructed on simplified LCL filter model corresponding
Second order line style extended mode observer indicates the second order line style extended mode observer by following formula:
Wherein,For the differential of second order line style extended mode observer, z (t) is the defeated of second order line style extended mode observer
Out, L is the gain vector of second order line style extended mode observer, TdFor time delay module,For ideal power network current；
Step 2: second order line style extended mode observer state z1And z2Y and f (t, y, w) will be tracked respectively；
Step 3: estimated state variable and total disturbance, will always disturb and own resonance integration.
5. a kind of uncertain parameter disturbance restraining method of LCL filter gird-connected inverter according to claim 4, special
Sign is: it is calculate by the following formula the gain vector of second-order linearity extended mode observer:
L=[β1β2]T (6)
Wherein, β1、β2It is adjustment parameter, T is it is expected to stablize the time.
6. a kind of uncertain parameter disturbance restraining method of LCL filter gird-connected inverter according to claim 4, special
Sign is: carrying out Laplace transform to second-order linearity extended mode observer expression formula and obtains the observer state z1And z2, lead to
Crossing following formula indicates z1And z2:
Wherein, s is Laplace operator, and r is reference input, and kp is controller gain.
7. a kind of uncertain parameter disturbance restraining method of LCL filter gird-connected inverter according to claim 1, special
Sign is: the step 4 specifically:
Step 1: carrying out feedback control to state error, SEF exports the reference signal from TD and the observer from ESO
Differential signal combines, and generates the intermediate voltage signal u controlled using nonlinear function0；
Step 2: compensating total disturbance in suppression loop, compensated total disturbance is indicated by following formula:
Wherein, u is compensated total disturbance, u0For using the voltage signal of the terminal point control on nonlinear function birthdate；
Step 3: output signal and input signal are indicated by following formula after suppression loop compensates total disturbance:
Wherein, kp is controller gain.
Power grid is considered as pure integral element, is controlled using linear scale controller, indicates that the linear scale controls by following formula
Device:
U (t)=kp(t(t)-z1(t)) (11)
Wherein, u (t) is linear scale controller, and t (t) is reference input, z1It (t) is to actually enter.
8. a kind of uncertain parameter disturbance restraining method of LCL filter gird-connected inverter according to claim 1, special
Sign is: the step 5 specifically:
Step 1: determining closed-loop pole according to desired stable time T, controller gain is obtained, observer gain is selected, makes
It obtains all observer characteristic values and is all located at-ωo, then have at this time:
Wherein, ωoFor observer bandwidth；
Step 2: obtaining the control strategy of control when observer characteristic value is in stable state, control plan is indicated by following formula
Slightly:
U (s)=Gc(s)(r(s)-H(s)y(s)) (13)
Wherein, u (s) is control strategy, GcIt (s) is controlling unit transmission function, H (s) is feedback element transmission function, and r (s) is
Input signal function, y (s) are output signal function；
Step 3: acquiring control output in a frequency domain, indicate that control in a frequency domain exports by following formula:
Y (s)=Gfy(s)f(s)+Gry(s)r(s) (16)
Wherein, f (s) is disturbance, GfyIt (s) is disturbance transfer function, Gry(s) reference input transmission function.
9. a kind of uncertain parameter disturbance restraining method of LCL filter gird-connected inverter according to claim 8, special
Sign is: when ignoring disturbance, then simplified control exports expression formula, indicates that simplified control exports expression formula by following formula:
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